Modular wall telephones in which a detachable plug connected to the telephone is mated with a jack in a mounting receptacle plate, have been common since the mid 1970's. Generally, the receptacle has a central aperture holding a jack recessed behind the plate and has two vertically spaced, headed studs. A modular plug terminating a line cord loosely extends through an opening in the base to reach a mating relation with the jack and connect the phone to the system, this connection being completed prior to the mounting of the phone on the receptacle plate. The base plate has vertically spaced keyhole openings for receiving the headed studs so that the head of the studs rests under the narrowed end of the keyhole to firmly mount the phone on the receptacle plate.
Within this general framework, U.S. Pat. No. 3,898,394 to Ward et al. shows a horizontally slidable, selectively operable latch member to engage the stud under the head and hold the engagement of phone to receptacle plate. U.S. Pat. No. 4,284,855 to Adams et al. shows a variation on the keyhole opening by rendering the sides of the opening yieldable to provide a latching action on the headed stud. Since there is no release mechanism, release is effected by pushing the phone to cause the yieldable sections to deform and enable the stud to pass the narrow waist section of the keyhole openings. U.S. Pat. No. 4,349,706 to Thompson shows a pivotal latch accessible from the interior of the base to latch and release the receptacle mounting.